| 1 | |
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| 2 | __all__ = ['Composer', 'ComposerError'] |
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| 3 | |
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| 4 | from error import MarkedYAMLError |
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| 5 | from events import * |
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| 6 | from nodes import * |
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| 7 | |
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| 8 | class ComposerError(MarkedYAMLError): |
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| 9 | pass |
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| 10 | |
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| 11 | class Composer(object): |
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| 12 | |
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| 13 | def __init__(self): |
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| 14 | self.anchors = {} |
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| 15 | |
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| 16 | def check_node(self): |
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| 17 | # Drop the STREAM-START event. |
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| 18 | if self.check_event(StreamStartEvent): |
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| 19 | self.get_event() |
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| 20 | |
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| 21 | # If there are more documents available? |
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| 22 | return not self.check_event(StreamEndEvent) |
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| 23 | |
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| 24 | def get_node(self): |
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| 25 | # Get the root node of the next document. |
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| 26 | if not self.check_event(StreamEndEvent): |
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| 27 | return self.compose_document() |
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| 28 | |
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| 29 | def get_single_node(self): |
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| 30 | # Drop the STREAM-START event. |
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| 31 | self.get_event() |
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| 32 | |
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| 33 | # Compose a document if the stream is not empty. |
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| 34 | document = None |
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| 35 | if not self.check_event(StreamEndEvent): |
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| 36 | document = self.compose_document() |
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| 37 | |
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| 38 | # Ensure that the stream contains no more documents. |
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| 39 | if not self.check_event(StreamEndEvent): |
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| 40 | event = self.get_event() |
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| 41 | raise ComposerError("expected a single document in the stream", |
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| 42 | document.start_mark, "but found another document", |
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| 43 | event.start_mark) |
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| 44 | |
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| 45 | # Drop the STREAM-END event. |
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| 46 | self.get_event() |
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| 47 | |
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| 48 | return document |
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| 49 | |
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| 50 | def compose_document(self): |
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| 51 | # Drop the DOCUMENT-START event. |
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| 52 | self.get_event() |
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| 53 | |
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| 54 | # Compose the root node. |
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| 55 | node = self.compose_node(None, None) |
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| 56 | |
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| 57 | # Drop the DOCUMENT-END event. |
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| 58 | self.get_event() |
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| 59 | |
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| 60 | self.anchors = {} |
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| 61 | return node |
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| 62 | |
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| 63 | def compose_node(self, parent, index): |
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| 64 | if self.check_event(AliasEvent): |
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| 65 | event = self.get_event() |
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| 66 | anchor = event.anchor |
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| 67 | if anchor not in self.anchors: |
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| 68 | raise ComposerError(None, None, "found undefined alias %r" |
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| 69 | % anchor.encode('utf-8'), event.start_mark) |
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| 70 | return self.anchors[anchor] |
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| 71 | event = self.peek_event() |
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| 72 | anchor = event.anchor |
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| 73 | if anchor is not None: |
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| 74 | if anchor in self.anchors: |
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| 75 | raise ComposerError("found duplicate anchor %r; first occurence" |
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| 76 | % anchor.encode('utf-8'), self.anchors[anchor].start_mark, |
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| 77 | "second occurence", event.start_mark) |
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| 78 | self.descend_resolver(parent, index) |
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| 79 | if self.check_event(ScalarEvent): |
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| 80 | node = self.compose_scalar_node(anchor) |
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| 81 | elif self.check_event(SequenceStartEvent): |
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| 82 | node = self.compose_sequence_node(anchor) |
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| 83 | elif self.check_event(MappingStartEvent): |
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| 84 | node = self.compose_mapping_node(anchor) |
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| 85 | self.ascend_resolver() |
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| 86 | return node |
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| 87 | |
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| 88 | def compose_scalar_node(self, anchor): |
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| 89 | event = self.get_event() |
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| 90 | tag = event.tag |
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| 91 | if tag is None or tag == u'!': |
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| 92 | tag = self.resolve(ScalarNode, event.value, event.implicit) |
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| 93 | node = ScalarNode(tag, event.value, |
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| 94 | event.start_mark, event.end_mark, style=event.style) |
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| 95 | if anchor is not None: |
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| 96 | self.anchors[anchor] = node |
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| 97 | return node |
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| 98 | |
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| 99 | def compose_sequence_node(self, anchor): |
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| 100 | start_event = self.get_event() |
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| 101 | tag = start_event.tag |
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| 102 | if tag is None or tag == u'!': |
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| 103 | tag = self.resolve(SequenceNode, None, start_event.implicit) |
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| 104 | node = SequenceNode(tag, [], |
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| 105 | start_event.start_mark, None, |
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| 106 | flow_style=start_event.flow_style) |
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| 107 | if anchor is not None: |
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| 108 | self.anchors[anchor] = node |
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| 109 | index = 0 |
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| 110 | while not self.check_event(SequenceEndEvent): |
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| 111 | node.value.append(self.compose_node(node, index)) |
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| 112 | index += 1 |
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| 113 | end_event = self.get_event() |
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| 114 | node.end_mark = end_event.end_mark |
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| 115 | return node |
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| 116 | |
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| 117 | def compose_mapping_node(self, anchor): |
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| 118 | start_event = self.get_event() |
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| 119 | tag = start_event.tag |
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| 120 | if tag is None or tag == u'!': |
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| 121 | tag = self.resolve(MappingNode, None, start_event.implicit) |
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| 122 | node = MappingNode(tag, [], |
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| 123 | start_event.start_mark, None, |
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| 124 | flow_style=start_event.flow_style) |
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| 125 | if anchor is not None: |
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| 126 | self.anchors[anchor] = node |
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| 127 | while not self.check_event(MappingEndEvent): |
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| 128 | #key_event = self.peek_event() |
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| 129 | item_key = self.compose_node(node, None) |
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| 130 | #if item_key in node.value: |
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| 131 | # raise ComposerError("while composing a mapping", start_event.start_mark, |
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| 132 | # "found duplicate key", key_event.start_mark) |
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| 133 | item_value = self.compose_node(node, item_key) |
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| 134 | #node.value[item_key] = item_value |
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| 135 | node.value.append((item_key, item_value)) |
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| 136 | end_event = self.get_event() |
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| 137 | node.end_mark = end_event.end_mark |
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| 138 | return node |
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| 139 | |
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